With the rapid development of the display technology, the touch panel has been widely used in people's lives. Compared with the conventional display device which merely provides a display function, the display device using the touch panel allows a user and a display control host to exchange information with each other. Therefore, the touch panel can completely or at least partially replace the common input device, so that the display device with the touch panel not only performs a display function but also performs a touch function.
The common touch panel can be classified into: a resistive touch panel, a capacitive touch panel, an electromagnetic touch panel and an infrared touch panel, etc. The capacitive touch panel works by means of the human's current induction. As shown in FIG. 1, when a finger touches the capacitive touch panel, a coupling capacitor is formed between the finger and the working area of capacitive touch panel (that is, a touch electrode 111 shown in FIG. 1) due to the human electric field. Since the working area is supplied with a high-frequency current in which case the capacitor is a direct conductor, a tiny current is sucked from the touch point by the finger. The position of the touch point is calculated according to the change in the capacitance of the touch point, thereby achieving the touch function.
However, in electronic terminals with the capacitive touch panel, finger is not the only medium to realize a touch process, and a stylus may also be a tool to realize a touch process. In the case that the touch panel is touched by a finger, a contact area in a touch process is relatively large due to the natural shape and size of the finger, and hence intensity of the current induced by the coupling capacitor is changed largely, so that the touch position is precisely calculated. However, when the touch panel is touched by a stylus, the contact area in a touch process is relatively small due to the shape and the size of the stylus, and hence the intensity of the current induced by the coupling capacitor is changed small so that it is difficult to determine the touch position, leading to a higher accurate operation requirement on the touch process.
Hence, in the capacitive touch panel of the related art, for example in the arrangement shown in FIG. 2A, to achieve the detection of the stylus, the common electrode 101 is generally arranged as a complex polygons, in order to allow the touch operation to be detected by more touch electrodes (that is, common electrodes 101). In the touch period, this arrangement indeed has a good effect on the touch operation, especially in the case of using the stylus. However, in the display period, the complex polygons of the common electrode 101 may lead to an abnormal display.
During the display process, pixel dots are refreshed row-by-row in display. In FIG. 2B, illustratively, a row a, a row b, a row c and a row d correspond to different rows of pixel electrodes. As the row a is displayed, the pixel electrodes of the row a are charged simultaneously, and an intensity Ca affected by the parasitic capacitor on the common electrode 101 is formed. As the pixels of the row b, the row c and the row d are refreshed, intensities Cb, Cc and Cd affected by the parasitic capacitors on the common electrode 101 are formed, respectively. Lengths of the pixels of the row a, the row b, the row c and the row d corresponding to the common electrode 101 are different, causing different intensities affected on the same common electrode 101. As shown in FIG. 2B, it is shown that Cb=Cc>Ca>Cd, and hence the perturbations on the common electrode 101 are also different. In FIG. 2B, the perturbation of the region between the row b and the row c is relatively large. Such a difference in the perturbations would cause the brightness of region 40 to be higher than the brightness of the region 41 in the display process for example, thus generating bright stripes in a lateral direction, as shown in FIG. 2C.
In FIG. 2D, positions A, B and C are different, and the distance between the chip and the positions A, B and C are also different. The recovery capabilities of the perturbations of common electrode 101 at the different positions are affected by the corresponding resistance variations due to such different distances. A smaller resistance value leads to a stronger anti-perturbation capability. That is, the recovery capabilities at the position A and the position C are poorer than the recovery capability at the position B, thus causing a greater perturbation at the position A and the position C. Such a difference in the recovery capabilities, for example, would cause the brightness of region 50 to be higher than that of region 51 in the display process, thus generating bright stripes in a vertical direction, as shown in FIG. 2E.
Due to the impact of the bright stripes in the lateral direction shown in FIG. 2C and the bright stripes in the vertical direction shown in FIG. 2E, alternately varying gray scales are formed on the screen, as shown in FIG. 2F. It should be noted that FIG. 2F merely illustratively and schematically shows the gray scales are varying alternately, and such black and white appearance on FIG. 2F is not a real display effect.